8372806: [lworld] x64: save bad values instead of rfp and lr above the extension space

[marc-chevalier]

That's the x86 counterpart of JDK-8371993.

I've added some comments, using the offsets given in frame_x86.hpp to make sure to put the frame start at the right place. In particular, the frame start is 2 pointer sizes under the sender's sp:

valhalla/src/hotspot/cpu/x86/frame_x86.hpp

Lines 61 to 62 in 3c41c2a

	// non-interpreter frames
	sender_sp_offset = 2,

Unlike aarch64, with x64 we have only one copy of rbp. As with aarch64, I had to get rid of an assert that can't be checked anymore. A small price to pay.

Now, in debug, instead of

pop    r13
sub    rsp,0x20
push   r13

we have

pop    r13
sub    rsp,0x20
mov    DWORD PTR [rsp-0x4],0xdeadda7a
mov    DWORD PTR [rsp-0x8],0xdeadda7a
sub    rsp,0x8

I've kept the pop r13 to limit the difference of behavior between debug and product builds: both will overwrite r13 with the return address, whether it's a good idea or not.

And at runtime, on my favorite compiler/valhalla/inlinetypes/CorrectlyRestoreRfp.java example, instead of the stack:

0x7fd7345fe660:	0x000000042724f5d0	0x00007fd7345fe750  <-- rsp
0x7fd7345fe670:	0xffffffffffffffff	0x00007fd740acc0f7
0x7fd7345fe680:	0x00007fd700000000	0x000000042724f5d0
0x7fd7345fe690:	0x000000056f517f28	0x00007fd7390002a6
0x7fd7345fe6a0:	0x00007fd72c90c8b3	0x0000000000000078  <--             #                | sp_inc
0x7fd7345fe6b0:	0x00007fd7345fe750	0x00007fd740541306  <-- rsp - 0x50  #            rbp | return address
0x7fd7345fe6c0:	0x000000056f49f4e0	0x000000042724f5d0  <--             #  String (arg2) | Object (arg3)
0x7fd7345fe6d0:	0x0000000000000000	0x00007fd740541306  <-- rsp - 0x70  # boolean (arg4) | return address
0x7fd7345fe6e0:	0x00007fd740541306	0x0000000000000000
0x7fd7345fe6f0:	0x000000042724f5d0	0x000000056f49f4e0

we have

0x7f93cfdfe660:	0x000000042724f5d0	0x00007f93cfdfe750  <-- rsp
0x7f93cfdfe670:	0xffffffffffffffff	0x00007f93e4acc107
0x7f93cfdfe680:	0x00007f9300000000	0x000000042724f5d0
0x7f93cfdfe690:	0x000000056f517fb0	0x00007f93dd0002a6
0x7f93cfdfe6a0:	0x00007f93d090c8b3	0x0000000000000078  <--             #                | sp_inc
0x7f93cfdfe6b0:	0x00007f93cfdfe750	0xdeadda7adeadda7a  <-- rsp - 0x50  #            rbp | >>>> bad word <<<<
0x7f93cfdfe6c0:	0x000000056f49f540	0x000000042724f5d0  <--             #  String (arg2) | Object (arg3)
0x7f93cfdfe6d0:	0x0000000000000000	0x00007f93e4541306  <-- rsp - 0x70  # boolean (arg4) | return address
0x7f93cfdfe6e0:	0x00007f93e4541306	0x0000000000000000
0x7f93cfdfe6f0:	0x000000042724f5d0	0x000000056f49f540

I had to problem list some virtual thread tests, in the same fashion as for aarch64, as it used the wrong return address. The assert I had to remove was a sign that only one of the return address is updated in case of deopt, so only one of them is reliable. To help with that, I've added frame::compiled_frame_details like for aarch64, that makes sure to do all the fixing internally.

Thanks,
Marc

---

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Issue

• JDK-8372806: [lworld] x64: save bad values instead of rfp and lr above the extension space (Enhancement - P4)

Reviewers

• Tobias Hartmann (@TobiHartmann - Committer)

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8372806: [lworld] x64: save bad values instead of rfp and lr above the extension space

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At the time when this comment was updated there had been 84 new commits pushed to the lworld branch:

• 69399ce: 8373875: [lworld] runtime/cds/DumpSymbolAndStringTable.java fails with --enable-preview
• e98a149: 8374028: [lworld] LoadableDescriptors order should be deterministic
• 1e6e72e: 8372686: [lworld] runtime/cds/serviceability/ReplaceCriticalClasses.java fails with --enable-preview
• ... and 81 more: https://git.openjdk.org/valhalla/compare/49bff14fef20d3edb0e8ae5d3d2c40449d248926...lworld

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[TobiHartmann]

Nice comments! The changes look good to me.